[USACO 2009 Feb Gold] Fair Shuttle (贪心+优先队列)

 1 #include <cstdio>
 2 #include <algorithm>
 3 #include <queue>
 4 #include <cstring>
 5 #define N 50005
 6 #define ll long long 
 7 using namespace std;
 8 
 9 int k,n,c,ans;
10 int sum[N];
11 struct COW{
12     int x,y,w;
13 }cow[N];
14 int cmp(COW s1,COW s2) {return s1.x<s2.x;}
15 struct node1{
16     int id;
17     friend bool operator<(const node1 &s1,const node1 &s2) 
18     {return cow[s1.id].y > cow[s2.id].y;}
19 };
20 node1 ins1(int idd){node1 w;w.id=idd;return w;}
21 struct node2{
22     int id;
23     friend bool operator<(const node2 &s1,const node2 &s2) 
24     {return cow[s1.id].y < cow[s2.id].y;}
25 };
26 node2 ins2(int idd){node2 w;w.id=idd;return w;}
27 int solve()
28 {
29     sort(cow+1,cow+k+1,cmp);
30     priority_queue<node1>q1;
31     priority_queue<node2>q2;
32     int j=1,cnt=0;
33     for(int i=1;i<=n;i++)
34     {
35         while(!q1.empty())
36         {
37             node1 p=q1.top();
38             if(cow[p.id].y==i)
39             {
40                 q1.pop();
41                 ans+=sum[p.id];
42                 cnt-=sum[p.id];
43                 sum[p.id]=0;
44             }else{
45                 break;
46             }
47         }
48         while(cow[j].x==i)
49         {
50             q1.push(ins1(j));
51             q2.push(ins2(j));
52             cnt+=cow[j].w;
53             sum[j]=cow[j].w;
54             j++;
55         }
56         while(cnt>c)
57         {
58             node2 p=q2.top();
59             if(cnt-sum[p.id]>c) 
60             {
61                 q2.pop();
62                 cnt-=sum[p.id];
63                 sum[p.id]=0;
64             }else{
65                 sum[p.id]-=(cnt-c);
66                 cnt=c;
67             }
68         }
69     }
70     return ans;
71 }
72 
73 int main()
74 {
75     scanf("%d%d%d",&k,&n,&c);
76     for(int i=1;i<=k;i++) scanf("%d%d%d",&cow[i].x,&cow[i].y,&cow[i].w);
77     printf("%d",solve());
78     return 0;
79 }